2&#39;-Benzothiazolyl-and 2&#39;-benzoxazolyl-2-benzimidazoles

ABSTRACT

Disclosed are compounds of Formula I, ##STR1## where either R 1 , R 2 , R 3  and R 4 , independently, are hydrogen, C 1-4  alkyl, C 1-4  alkoxy, halogen, cyano, carboxy, alkoxy(C 1-4 )carbonyl, --CONR 6  R 7 , --SO 2  NR 6  R 7 , --SO 2  R 8 , alkyl(C 1-4 )carbonyloxy, or C 1-4  alkoxy monosubstituted by phenyl, alkoxy(C 1-4 )carbonyl, cyano, carboxy or --CONR 6  R 7 , 
     with the proviso that a maximum of one of R 1  and R 2  and a maximum of one of R 3  and R 4  can signify a group selected from cyano, carboxy, alkyl (C 1-4 )carbonyloxy, --CONR 6  R 7 , --SO 2  NR 6  R 7  and --SO 2  R 8 , 
     or one or both pairs R 1  and R 2 , and R 3  and R 4 , are on adjacent carbon atoms and form a fused benzene ring, any pair not forming a ring being as defined above, 
     R 5  is C 1-4  alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl, C 2-4  alkenyl, carboxy, C 1-4  alkoxycarbonyl or --CONR 6  R 7  ; or unsubstituted phenyl, 
     R 6  and R 7 , independently, are hydrogen or C 1-4  alkyl, 
     R 8  is C 1-4  alkyl, and 
     X is O or S, 
     in free base, acid addition salt or quaternary ammonium salt form, their production and use as optical brightening agents for polyacrylonitrile.

The invention relates to benzimidazole derivatives.

The invention provides compounds of formula I, ##STR2## where either R₁,R₂, R₃ and R₄, independently, are hydrogen, C₁₋₄ alkyl, C₁₋₄ alkoxy,halogen, cyano, carboxy, alkoxy(C₁₋₄)carbonyl, --CONR₆ R₇, --SO₂ NR₆ R₇,--SO₂ R₈, alkyl(C₁₋₄)carbonyloxy, or C₁₋₄ alkoxy monosubstituted byphenyl, alkoxy(C₁₋₄)carbonyl, cyano, carboxy or --CONR₆ R₇,

with the proviso that a maximum of one of R₁ and R₂ and a maximum of oneof R₃ and R₄ can signify a group selected from cyano, carboxy, alkyl(C₁₋₄)carbonyloxy, --CONR₆ R₇, --SO₂ NR₆ R₇ and --SO₂ R₈,

or one or both pairs R₁ and R₂, and R₃ and R₄, are on adjacent carbonatoms and form a fused benzene ring, any pair not forming a ring beingas defined above,

R₅ is C₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy, cyano,phenyl, C₂₋₄ alkenyl, carboxy, C₁₋₄ alkoxycarbonyl or --CONR₆ R₇ ; orunsubstituted phenyl,

R₆ and R₇, independently, are hydrogen or C₁₋₄ alkyl,

R₈ is C₁₋₄ alkyl, preferably methyl, and

X is O or S,

which compounds are in free base, acid addition salt or quaternaryammonium salt form.

By "halogen", as used above, is meant chlorine or bromine, chlorinebeing the preferred halogen.

In the compounds of formula I, R₁ and R₂ preferably are, independently,hydrogen; C₁₋₄ alkyl; chlorine; or C₁₋₄ alkoxy, unsubstituted ormono-substituted by phenyl, alkoxy(C₁₋₄)carbonyl, carboxy, cyano or--CONR₆ R₇ or, together, form a fused benzene ring. More preferably oneof R₁ and R₂ is hydrogen or C₁₋₄ alkyl, the other C₁₋₄ alkyl; chlorine;or C₁₋₄ alkoxy, unsubstituted or mono-substituted by phenyl oralkoxy(C₁₋₄)carbonyl, any alkyl as R₁ or R₂ preferably being methyl andany unsubstituted alkoxy preferably being C₁₋₂ alkoxy, more preferablymethoxy. Still more preferably, one of R₁ and R₂ is hydrogen, and mostpreferably the other is C₁₋₄ alkoxy, unsubstituted or mono-substitutedby phenyl or alkoxy (C₁₋₄)carbonyl.

Of R₃ and R₄, preferably one is hydrogen or C₁₋₄ alkyl, the otherhydrogen, C₁₋₄ alkyl, chlorine or --SO₂ R₈, more preferably one beinghydrogen, the other being hydrogen or C₁₋₄ alkyl. Again, any alkyl as R₃or R₄ is preferably methyl.

Where the R₁ /R₂ or R₃ /R₄ bearing ring is mono substituted, thesubstituent is preferably in the 5- or 6-position, more preferably inthe 6-position, especially for the R₁ /R₂ bearing ring, and, whendi-substituted, one of the substituents is preferably in the 6-position.Preferably the R₁ /R₂ bearing ring is mono or disubstituted, morepreferably mono-substituted.

The preferred forms of the compounds of formula I are the acid additionsalt and quaternary ammonium salt forms, particularly the latter. Suchforms arise from the basic nature of the heterocyclic nitrogens presentboth in the benzimidazole and the benzoxazole or benthiazole rings.Whilst it is possible to protonate or quaternise both rings in thecompounds of formula I using relatively forcing conditions, it ispossible, because of the higher basicity of the benzimidazole ring, toprotonate or quaternise this ring alone and, indeed, those acid additionsalt and quaternary ammonium salts of the compounds of formula I,wherein only the benzimidazole ring is protonated or quaternized, arepreferred.

As examples of quaternising groups may be given C₁₋₄ alkyl, e.g. methyl,ethyl, isopropyl, n-propyl, n-butyl, C₁₋₄ alkyl mono-substituted byphenyl, e.g. benzyl, C₁₋₄ alkyl mono-substituted by C₁₋₂ alkoxycarbonyl,e.g. --CH₂ CO₂ CH₃ and --CH₂ CO₂ C₂ H₅, C₁₋₄ alkyl mono-substituted by--CONR₆ R₇, e.g. --CH₂ CONH₂ and --CH₂ CON(CH₃)₂, --CH₂ --CH═CH₂, --CH₂--C(CH₃)═CH₂, --CH₂ COOH and --CH₂ CN. The anion may be anynon-chromophoric anion.

Since the intended use of the compounds is as optical brighteningagents, positions of and combinations of substituents which yieldcompounds having an unduly strong coloured hue should, of course, beavoided.

The preferred compounds of the invention may be represented by theformula I', ##STR3## where R₂ ' is C₁₋₄ alkyl; chlorine; or C₁₋₄ alkoxy,unsubstituted or mono-substituted by phenyl or alkoxy(C₁₋₄)carbonyl,

and R₁ ' is H or C₁₋₄ alkyl,

one of R₃ ' and R₄ ' is hydrogen or C₁₋₄ alkyl, (preferably methyl), theother hydrogen, C₁₋₄ alkyl (preferably methyl), chlorine or --SO₂ CH₃,preferably one being hydrogen or methyl, the other being hydrogen,

R₉ is C₁₋₄ alkyl, unsubstituted or mono-substituted byalkoxy(C₁₋₂)carbonyl, phenyl or --CONR₆ R₇,

and A.sup.⊖ is a non-chromophoric anion.

In compounds I', R₉ is preferably unsubstituted C₁₋₄ alkyl, morepreferably methyl or ethyl. R₅, both in compounds I and I', ispreferably C₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy,cyano, phenyl or alkoxy(C₁₋₄)carbonyl, more preferably C₁₋₄ alkyl,unsubstituted or mono-substituted by phenyl or alkoxy-(C₁₋₄)carbonyl. Inany hydroxy substituted alkyl as R₅, the hydroxy group is preferablyother than on the α-carbon atom, it preferably being on the β-carbonatom.

R₂ ' is preferably C₁₋₄ alkoxy, unsubstituted or monosubstituted byphenyl or alkoxy(C₁₋₄)carbonyl. R₁ ' is preferably hydrogen.

X, both in compounds I and I', is preferably O.

As a further preferred class of compounds of formula I may be giventhose of formula I", ##STR4## where R₂ " is C₁₋₄ alkoxy, unsubstitutedor mono-substituted by phenyl or alkoxy(C₁₋₄)carbonyl, more preferablymethoxy or alkoxy(C₁₋₂)carbonylmethoxy, most preferably methoxy,

one of R₃ " and R₄ " is hydrogen or methyl, the other being hydrogen,

R₅ " is C₁₋₄, preferably C₁₋₂, alkyl, unsubstituted or mono-substitutedby phenyl or alkoxy(C₁₋₄)carbonyl, and

R₉ " is C₁₋₄ alkyl, preferably methyl or ethyl,

R₅ " in formula I", and indeed R₅ in formulae I and I' is mostpreferably methyl, ethyl, benzyl or alkoxy(C₁₋₂)carbonyl methyl.

As examples of non-chromophoric anions as A.sup.⊖ may be given methyl,ethyl and propyl sulphate anions and the chloride, bromide,p-toluene-sulphonate, chlorozincate and benzene-sulphonate anions. Aswill be appreciated, however, the anion may be any conventional in theoptical brightener art.

The invention also provides a process for the production of compounds offormula I, characterised by

(a). reacting a compound of formula II, ##STR5## with a compound offormula III, ##STR6## where Y is chlorine or bromine, preferablychlorine, (b). oxidising a compound of formula V ##STR7## wherein either(a). P is --XH and Q is H, and U and T form a direct bond between theatoms to which they are attached,

or (b). P and Q, together form --X--, and U and T are both hydrogen,

in case (a). the compound optionally being in protonized or quaternizedform,

(c). obtaining a compound of formula I, in which R₅ is other thenphenyl, by alkylation of a compound of formula IV, ##STR8## in which R₁⁰, R₂ ⁰, R₃ ⁰ and R₄ ⁰ each have a significance of R₁, R₂, R₃ and R₄,above, or one or more thereof signifies hydroxy,

the alkylation being carried out with an alkylation agent which yields aC₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl,C₂₋₄ alkenyl, carboxy, alkoxy(C₁₋₄)carbonyl or --CONR₆ R₇, alkylatinggroup when R₁ ⁰, R₂ ⁰, R₃ ⁰ and R₄ ⁰ have significances of R₁, R₂, R₃and R₄, or with an alkylating agent which yields a C₁₋₄ alkyl,unsubstituted or mono-substituted by phenyl, alkoxy(C₁₋₄)carbonyl,cyano, carboxy or --CONR₆ R₇, alkylating group when one or more of R₁ ⁰to R₄ ⁰ is hydroxy, simultaneous alkylation of said hydroxy group takingplace in the latter case, and, where desired, converting any compound offormula I, obtained in free base form, into acid addition salt orquaternary ammonium salt form.

Process (a). is suitably carried out in an inert polar solvent, such asin water, ethanol, methanol, isopropanol, cellosolve, dimethylformamideor mixtures thereof. A suitable reaction temperature is -50° to +150°C., preferably 0° to 100° C. The reaction is suitably carried out in thepresence of a base such as sodium carbonate, acetate, hydroxide ormethoxide, potassium hydroxide, triethylamine or pyridine.

Process (b). is suitably carried out in an inert solvent, e.g. water,ethanol, acetone, acetic acid, dimethylformamide, xylene, chlorobenzene,carbon tetrachloride, chloroform or pyridine. Suitable oxidizing agentsinclude air, manganese dioxide, lead tetraacetate, sodium hypochlorite,nitrobenzene and chloranil. A suitable reaction temperature is from 0°to 200° C., preferably 20° to 150° C.

Process (c). is suitably carried out in an inert solvent, such aschloroform, trichloroethylene, benzene, toluene, chlorobenzene, dioxan,dimethylformamide, methanol, ethanol, propanol, cellusolve or water. Thealkylating agent is, of course, dictated by the desired significance ofR₅ in the resulting compounds formula I, and the desired significance ofR₁ to R₄ when one of R₁ ⁰ to R₄ ⁰ in compound IV is hydroxy, and ischosen accordingly. As examples of alkylating agents may be givendimethyl and diethyl sulphate, alkyl halides such as methyl, ethyl andpropyl iodide and butyl bromide, methyl p-toluenesulphonate, benzylchloride, ethylene oxide, ethylbromoacetate, allyl chloride,acrylonitrile and acrylamide. The reaction is preferably carried out inthe presence of a base, such as sodium, potassium or calcium carbonateor hydroxide, calcium or magnesium oxide, magnesium hydroxide,triethylamine or benzyltrimethylammonium hydroxide. A suitable reactiontemperature is from -50° to +200° C., preferably 0° to 100° C. As willbe appreciated, during such alkylation, any carboxy group present in themolecule will likely be alkylated. Where such occurs, hydrolysis of theester group can subsequently be effected.

The conversion of the free base forms of compounds of formula I intoacid addition salt or quaternary ammonium salt form may be carried outin conventional manner, employing conventional protonating orquaternising agents. As examples of quaternising agents may be givendimethyl and diethylsulphates, methyl, ethyl and propyl bromides, methylp-toluenesulphonate, ethylene oxide, benzyl chloride,ethylchloroacetate, allyl bromide, bromo-acetic acid, chloro-acetamideand chloro-N,N-dimethylacetamide. Suitable protonating agents includemineral and organic acids. Suitable solvents for the quaternisation orprotonisation include trichloroethylene, toluene, chlorobenzene, dioxan,dimethylformamide, methanol, ethanol and water. A suitable reactiontemperature is from 0° to 150° C., preferably 20° to 100° C. Preferablyat least one equivalent of protonating or quaternization agent isemployed. If desired, and where the quaternating group is the same asR₅, the quaternization can be carried out simultaneously with process(c). i.e. alkylation and quaternisation being effected at the same time,employing, for example, an excess of the alkylating agent. In this case,a base, e.g. as set out for process (c)., is preferably employed.

As will be appreciated, interconversions from one compound of formula Ito another may be carried out, e.g. by conversion of carboxy or nitrilegroup(s) into ester and amide group(s), by conversion of nitrile, amideand ester group(s) into carboxy group(s) and interconversion of theanions in the protonated and quaternized compounds.

The resulting compounds of formula I may be isolated and purified inconventional manner.

The compounds of formulae II to V are either known or may be obtainedfrom available starting materials in analogous manner to similar knowncompounds. For example, the compounds of formula IV are convenientlyprepared in analogous manner to compounds I, e.g. in analogy to process(a)., but employing starting materials having hydrogen in place of R₅.

The compounds of formula I are optical brightening agents, beingespecially indicated for use in the brightening of substrates,preferably textile substrates, comprising or consisting ofpolyacrylonitrile polymers or acrylonitrile copolymers, suchco-polymers, for example, consisting of more than 80-95% acrylonitrilecopolymerised with 20 to 5% vinyl acetate, vinyl pyridine, vinylchloride, vinylidene chloride or acrylic acid, acrylic ester,methacrylic acid or methacrylic ester.

The compounds of formula I may be applied in conventional manner to suchsubstrates which may, for example, be in fibre, filament, woven,knitted, non-woven etc. form, e.g. from an aqueous bath, preferablyunder acid conditions, and in the presence or absence of chloritebleach. The amount of brightener used, based on the weight of thesubstrate is generally in the range of from 0.001 to 0.5%, preferably0.01 to 0.2%. The compounds in protonated or quaternized form,particularly those of formula I', have good water-solubility and havenotable stability to bleaching agents such as sodium chlorite andmetabisulphite. The brightenings obtained generally have good lightfastness properties.

The compound of formula I may also be used in the mass brightening oftextile filaments, e.g. by incorporation in spinning melts or solutions.

The following Examples illustrate the invention.

EXAMPLE 1 (process (c))

2-Trichloromethylbenzimidazole (36.6 g) and 2-amino-5-methoxyphenol(24.2 g) were stirred together in 95% ethanol (300 ml). Triethylamine(47.9 g) was added dropwise to the stirred mixture over a period of 15minutes, keeping the temperature below 30° C. by external cooling. Thesolution was then stirred at 20°-25° C. for a further 2 hours. Water wasthen added and the mixture stirred for 30 minutes. The precipitated oilsolidified and was filtered off, dried and crystallised from acetone andthen n-butanol. 10 g of the resultant fawn coloured solid was mixed withanhydrous potassium carbonate (5.2 g), sodium iodide (5.7 g), benzylchloride (3.3 g) acetone (50 ml) and dimethylformamide (20 ml) and themixture stirred and heated under reflux for 41/2 hours. The resultantmixture was filtered hot and the filtrate cooled to 0° C. Theprecipitate was filtered, washed with acetone and dried to give acompound of formula ##STR9## as a fawn coloured solid.

EXAMPLE 2-11

The compounds listed in the following table were prepared by a proceduresimilar to that described in Example 1 but employing the appropriatestarting materials and reagents. They are of formula

    __________________________________________________________________________     ##STR10##                                                                                                    Physical                                      Example                                                                            X Rx Ry  Rz  Rq   R.sub.5  appearance                                    __________________________________________________________________________    2    O H  H   OCH.sub.3                                                                         H    CH.sub.3 pale fawn                                                                     solid                                         3    O H  H   CH.sub.3                                                                          H    CH.sub.2 Ph                                                                            colourless                                                                    solid                                         4    S H  H   OCH.sub.3                                                                         H    CH.sub.3 pale yellow                                                                   solid                                         5    O CH.sub.3                                                                         H   CH.sub.3                                                                          H    CH.sub.2 Ph                                                                            white solid                                   6    O CH.sub.3                                                                         H   CH.sub.3                                                                          SO.sub.2 CH.sub.3                                                                  CH.sub.2 Ph                                                                            white solid                                   7    O H  H   CH.sub.3                                                                          SO.sub.2 CH.sub.3                                                                  CH.sub.2 Ph                                                                            white solid                                   8    O H  OCH.sub.3                                                                         H   H    CH.sub.3 pale yellow                                                                   solid                                         9    O H  OCH.sub.3                                                                         H   H    CH.sub.2CHCH.sub.2                                                                     white solid                                   10   O H  H   OCH.sub.3                                                                         H    CH.sub.2 CO.sub.2 Et                                                                   white solid                                   11   O H  Cl  OCH.sub.3                                                                         H    CH.sub.3 white solid                                   11a  O CH.sub.3                                                                         H   CH.sub.3                                                                          H    CH.sub.2 CO.sub.2 Et                                                                   white solid                                   11b  O H  H   OCH.sub.3                                                                         CH.sub.3                                                                           CH.sub.3 white solid                                   11c  O H  H   OCH.sub.3                                                                         Cl   CH.sub.3 white solid                                   11d  O H  H   OCH.sub.3                                                                         H    CH.sub.2 CO.sub.2 CH.sub.3                                                             white solid                                   11e  O H  H   OEt H    CH.sub.3 white solid                                   __________________________________________________________________________     Ph = phenyl                                                                   Et = ethyl                                                               

EXAMPLE 12 (quaternization)

The compound described in Example 1 (5.4 g) was mixed with dioxan (100ml) and dimethyl sulphate (1.9 g) and the mixture heated under refluxfor 1 hour then cooled to 20° C. and filtered to give a compound offormula ##STR11## as a pale yellow solid.

EXAMPLE 13

Compounds of the following table were also prepared by a proceduresimilar to that described in Example 12 but employing appropriatestarting materials. They are of formula

    __________________________________________________________________________     ##STR12##                                                                                                              Physical                            Ex.                                                                              X Rx Ry  Rz  Rq   R.sub.9                                                                              R.sub.5 Anion.sup.⊖                                                                 Appearance                          __________________________________________________________________________    14 O H  H   CH.sub.3                                                                          H    CH.sub.3                                                                             CH.sub.2 Ph                                                                           CH.sub.3 SO.sub.4.sup.⊖                                                     colourless                                                                    solid                               15 O H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               16 S H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     yellow solid                        17 O CH.sub. 3                                                                        H   CH.sub.3                                                                          H    CH.sub.3                                                                             CH.sub.2 Ph                                                                           Cl.sup.⊖                                                                    white solid                         18 O CH.sub.3                                                                         H   CH.sub.3                                                                          SO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                             CH.sub.2 Ph                                                                           CH.sub.3 SO.sub.4.sup.⊖                                                     white solid                         19 O H  H   CH.sub.3                                                                          SO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                             CH.sub.2 Ph                                                                           CH.sub.3 SO.sub.4.sup.⊖                                                     white solid                         20 O H  OCH.sub.3                                                                         H   H    CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               21 O H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             CH.sub.2 CHCH.sub.2                                                                   CH.sub.3 SO.sub.4.sup.⊖                                                     white solid                         22 O H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             CH.sub.2 CO.sub.2 Et                                                                  CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               23 O H  Cl  OCH.sub.3                                                                         H    CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               24 O H  H   OCH.sub.3                                                                         H    C.sub.2 H.sub.5                                                                      CH.sub.2 CO.sub.2 Et                                                                  CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               25 O H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             C.sub.2 H.sub.4 CN                                                                    CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               26 O H  H   OCH.sub.3                                                                         H    CH.sub.3                                                                             C.sub.2 H.sub.4 CO.sub.2 CH.sub.3                                                     1/2ZnCl.sub.4.sup.⊖                                                         pale yellow                                                                   solid                               26a                                                                              O CH.sub.3                                                                         H   CH.sub.3                                                                          H    CH.sub.2 CO.sub.2 Et                                                                 CH.sub.2 CO.sub.2 Et                                                                  Br.sup.⊖                                                                    pale yellow                                                                   solid                               26b                                                                              O CH.sub.3                                                                         H   CH.sub.3                                                                          H    CH.sub.2 CO.sub.2 Et                                                                 CH.sub.2 Ph                                                                           Br.sup.⊖                                                                    pale yellow                                                                   solid                               26c                                                                              O CH.sub.3                                                                         H   CH.sub.3                                                                          SO.sub.2 CH.sub.3                                                                  CH.sub.2 CO.sub.2 Et                                                                 CH.sub.2 Ph                                                                           Br.sup.⊖                                                                    pale yellow                                                                   solid                               26d                                                                              O H  H   OCH.sub.3                                                                         CH.sub.3                                                                           CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               26e                                                                              O H  H   OCH.sub.3                                                                         Cl   CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               26f                                                                              O H  H   OCH.sub.3                                                                         H    CH.sub.2 CO.sub.2 CH.sub.3                                                           CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               26g                                                                              O H  H   OC.sub.2 H.sub.5                                                                  H    CH.sub.3                                                                             CH.sub.3                                                                              CH.sub.3 SO.sub.4.sup.⊖                                                     pale yellow                                                                   solid                               __________________________________________________________________________     Ph = phenyl                                                                   Et = ethyl                                                               

EXAMPLE 27 (process (c) with simultaneous quaternisation)

2-Trichloromethylbenzimidazole (23.6 g) and 1-amino-2-hydroxynaphthalenehydrochloride (19.6 g) were stirred together in 2-ethoxyethanol (100 ml)whilst triethylamine (40.4 g) was added dropwise with external coolingto keep the temperature of the reaction mixture below 30° C. The mixturewas stirred at ambient temperature for a further 17 hours and pouredinto water (500 ml). The precipitate was filtered, dried andcrystallised from dioxan. 7 g of the resultant fawn coloured solid wasstirred in dioxan (30 ml) together with magnesium oxide (0.5 g) anddimethyl sulphate (6.2 g). The mixture was heated to reflux, stirredunder reflux for 17 hours, cooled to 20° C. and filtered.Crystallisation of the crude solid product from isopropanol gave acompound of formula ##STR13## as a yellow coloured solid.

EXAMPLE 28 (Process (c))

6-Hydroxy-2(2')-benzimidazolyl benzoxazole (100 g), ethyl bromoacetate(166.3 g), anhydrous potassium carbonate (55.0 g) and acetone (600 ml)were stirred together under reflux for 3 hours. The solution was thenfiltered hot to remove inorganic salts and 300 ml of acetone distilledout. The solution was then cooled to 0° C. and the precipitated solidfiltered off and dried to give a compound of formula ##STR14## as awhite solid. 6-Hydroxy-2(2')-benzimidazolyl benzoxazole was prepared bya procedure similar to that described in Example 1, above, but employingthe appropriate starting materials.

EXAMPLE 29

By proceeding as described in Example 28, but employing benzyl chloridein place of ethyl bromoacetate, the compound of formula ##STR15## isobtained as a white solid.

EXAMPLE 30 (Quaternisation)

The compound described in Example 28 (4.5 g) was mixed with dioxan (25ml) and dimethyl sulphate (1.48 g) and the mixture heated under refluxfor 2 hours, then cooled to 20° C. and filtered to give the compound offormula ##STR16## as a white solid.

EXAMPLE 31

Following the procedure described in Example 30, but employing thecompound of Example 29 in place of the compound of Example 28, there isobtained the compound of formula ##STR17## as a pale yellow solid.

EXAMPLE 32 (process (c))

2-Trichloromethylbenzimidazole (36.6 g) and 2-amino-5-methoxy phenol(24.2 g) were stirred together in 95% ethanol (300 ml), triethylamine(47.9 g) was added dropwise to the stirred mixture over a period of 15minutes, keeping the temperature below 30° C. by external cooling. Thesolution was then stirred at 20°-25° C. for a further 2 hours. Water wasthen added and the mixture stirred for 30 minutes. The precipitated oilsolidified, and was filtered off and crystallised from acetone and thenbutanol. 13.05 g of the resultant fawn coloured solid was stirred underreflux in dioxan (50 ml) with acrylonitrile (9 g) and benzyl trimethylammonium hydroxide 40% W/W aqueous solution (0.5 ml) for 17 hours. Thesolution was then cooled to 40° C. and added to 100 cc of water. Theprecipitated solid was filtered, washed with water and dried to give thecompound of formula ##STR18## as a fawn coloured solid.

EXAMPLE 33

The compound of formula ##STR19## was obtained as a white solid in asimilar way to the compound described in Example 32 but using methylacrylate instead of acrylonitrile.

EXAMPLE 34

The compound of formula ##STR20## was obtained as a white solid in asimilar way to the compound described in Example 1, but usingappropriate starting materials and reagents.

EXAMPLE 35

The compound of formula ##STR21## was obtained as a pale yellow solid ina similar way to the compound described in Example 12 but usingappropriate starting materials and reagents.

EXAMPLE 36 (process (a))

1-Methyl-2-trichloromethylbenzimidazole (2.5 g) and2-amino-5-methoxyphenol (1.4 g) were stirred together in 95% ethanol (25ml) and triethylamine (1 g) added dropwise to the stirred mixture,keeping the temperature below 30° C. by external cooling. The mixturewas then heated to the boil and stirred under reflux for 2 hours. Themixture was then cooled to 20° C., filtered and the solid washed withwater and dried to give the compound described in Example 2 as a palefawn solid.

EXAMPLE 37 (protonation)

The compound described in Example 2 (5 g) was stirred in water (25 ml)and concentrated hydrochloric acid (36% w/w) (5 g) was added. Themixture was heated to the boil to give a clear solution and then thesolution was cooled to 20° C. The resulting solid precipitate wasfiltered off and washed with a little 20% w/w hydrochloric acid solutionand dried to give the compound of formula ##STR22## as a pale yellowsolid.

EXAMPLE 38 (process (b))

2-Hydroxy-4-methoxy-N-[(1,3-dimethylbenzimidazoliumyl)-2-methylidene]anilinemethosulphate(7.5 g) was stirred in glacial acetic acid (25 ml) and manganese dioxide(2.25 g) added. The mixture was warmed to reflux and stirred underreflux for 30 minutes and then screened to remove excess manganesedioxide. The solution was evaporated, to remove acetic acid and water(20 ml) added. The mixture was warmed until a clear solution wasobtained and then the solution cooled to 20° C. and the precipitatefiltered, washed with a little water and dried at 80° C. to give thecompound described in Example 15 as a pale yellow solid.

The2-hydroxy-4-methoxy-N-[(1,3-dimethylbenzimidazoliumyl)-2-methylidene]anilinemethosulphate used in the above example was prepared as follows:

2-Amino-5-methoxyphenol (50.5 g) was added to isobutanol (200 ml) and2-dichloromethylbenzimidazole hydrochloride (86 g) and the mixturestirred at 20°-25° C. as triethylamine (110 g) was added dropwise over aperiod of one hour. The mixture was stirred at 20°-25° C. for sixteenhours, the solid filtered off, washed with isobutanol and then water anddried at 80° C. to give2-hydroxy-4-methoxy-N-(benzimidazolyl-2-methylidene)-aniline as a palefawn coloured solid.2-Hydroxy-4-methoxy-N-(benzimidazolyl-2-methylidene)-aniline (13.4 g)and magnesium oxide (2.0 g) were mixed in 1,2-dichloroethane (50 ml).The mixture was stirred and heated to the boil and dimethyl sulphate(13.9 g) added dropwise to the refluxing mixture over 30 minutes. Themixture was stirred at reflux for a further 2 hours, then cooled to 20°C. and filtered. The solid was washed with 1,2-dichloroethane and driedat 70° C. to give2-hydroxy-4-methoxy-N[(1,3-dimethylbenzimidazoliumyl)-2-methylidene]-anilinemethosulphate as a yellow solid.

APPLICATION EXAMPLES

(A). A 5 gram piece of polyacrylonitrile was entered at 40° C. into 200mls of a solution containing 5 milligrams of the compound described inExample 12 and 100 milligrams of formic acid. The temperature of thebath was raised to 90°-95° C. during 30 minutes then maintained at90°-95° C. for a further 60 minutes. The fabric was rinsed well in hotthen cold demineralized water and dried at 80° C. The treated piece wasbrilliantly white compared to the untreated fabric. Similar results wereobtained when the compound of Example 12 was replaced by the compound ofExample 30.

(B). A 5 gram piece of polyacrylonitrile was entered at 40° C. into 200mls of a solution containing 10 milligrams of the compound described inExample 15, 400 milligrams of sodium chlorite, 400 milligrams of aphosphate based buffer salt and sufficient formic acid to adjust the pHof the bath to 3.5. The temperature of the agitated bath was increasedto 90°-95° C. during 30 minutes and maintained at 90°-95° C. for afurther 60 minutes. The piece was then anti-chlored for 10 minutes in200 mls of a solution containing 400 milligrams of sodiummetabisulphite, well rinsed with demineralized water and finally driedat 80° C. under tension. The treated piece was brilliantly whitecompared to the untreated material. Similar results were obtained whenthe compound of Example 15 was replaced by the compound of Example 31.

What is claimed is:
 1. A compound of the formula ##STR23## where R₂ ' isC₁₋₄ alkyl; chlorine; or C₁₋₄ alkoxy, unsubstituted or mono-substitutedby phenyl or alkoxy(C₁₋₄)carbonyl,one of R₃ ' and R₄ ' is hydrogen andthe other is hydrogen, or methyl, R₅ is C₁₋₄ alkyl, unsubstituted ormono-substituted by hydroxy, cyano, phenyl, C₂₋₄ alkenyl, carboxy, C₁₋₄alkoxycarbonyl or --CONR₆ R₇ ; or unsubstituted phenyl, R₆ and R₇,independently, are hydrogen or C₁₋₄ alkyl, R₉ is C₁₋₄ alkyl,unsubstituted or mono-substituted by alkoxy(C₁₋₂)carbonyl, phenyl or--CONR₆ R₇, X is O or Sand A.sup.⊖ is a non-chromophoric anion.
 2. Acompound of claim 1, wherein R₂ ' is C₁₋₄ alkoxy, unsubstituted ormono-substituted by phenyl or alkoxy(C₁₋₄)carbonyl.
 3. A compound ofclaim 1, wherein R₉ is unsubstituted C₁₋₄ alkyl.
 4. A compound of claim3, wherein R₉ is methyl or ethyl.
 5. A compound of claim 1, wherein R₅is C₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy, cyano,phenyl or alkoxy(C₁₋₄)carbonyl.
 6. A compound of claim 5, wherein R₅ isC₁₋₄ alkyl, unsubstituted or mono-substituted by phenyl oralkoxy(C₁₋₄)carbonyl.
 7. A compound of claim 6, wherein R₅ is methyl,ethyl, benzyl or alkoxy(C₁₋₂)carbonyl methyl.
 8. A compound of claim 1,wherein R₅ is C₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy,cyano, phenyl or alkoxy(C₁₋₄)carbonyl.
 9. A compound of claim 1, whereinX is O.
 10. A compound of claim 1, of formula I" ##STR24## where R₂ " isC₁₋₄ alkoxy, unsubstituted or mono-substituted by phenyl oralkoxy(C₁₋₄)carbonyl,one of R₃ " and R₄ " is hydrogen or methyl, theother being hydrogen, R₅ " is C₁₋₄ alkyl, unsubstituted ormono-substituted by phenyl or alkoxy(C₁₋₄)carbonyl, and R₉ " is C₁₋₄alkyl.
 11. A compound of claim 10, wherein R₂ " is methoxy oralkoxy(C₁₋₂)carbonyl methoxy.
 12. A compound of claim 11, wherein R₂ "is methoxy.
 13. A compound of claim 10, wherein R₅ " is C₁₋₂ alkyl,unsubstituted or mono-substituted by phenyl or alkoxy(C₁₋₄)-carbonyl.14. A compound of claim 10, wherein R₉ " is methyl or ethyl.
 15. Acompound of claim 10, wherein R₅ " is methyl, ethyl, benzyl oralkoxy(C₁₋₂)carbonyl methyl.
 16. A compound of claim 1, of formula##STR25##
 17. A compound of claim 1, of formula ##STR26##
 18. A compoundof claim 1, of formula ##STR27##
 19. A compound of claim 1, of formula##STR28##
 20. A compound of claim 1, of formula ##STR29##
 21. A compoundof claim 1, wherein R₂ ' is C₁₋₄ alkyl, C₁₋₄ alkoxy or chlorine, one ofR₃ ' and R₄ ' is hydrogen, the other hydrogen or methyl and R₉ is C₁₋₄alkyl, unsubstituted or mono-substituted by C₁₋₂ alkoxy-carbonyl.
 22. Acompound of claim 21, wherein R₃ ' and R₄ ' are both hydrogen.
 23. Acompound of claim 1, wherein R₂ ' is C₁₋₄ alkoxy, mono-substituted byphenyl or by alkoxy(C₁₋₄)carbonyl, one of R₃ ' and R₄ ' is hydrogen, theother hydrogen or methyl and R₉ is C₁₋₄ alkyl, unsubstituted ormono-substituted by C₁₋₂ alkoxy-carbonyl.
 24. A compound of claim 23,wherein R₃ ' and R₄ ' are both hydrogen.
 25. A compound of claim 23,wherein R₅ is C₁₋₄ alkyl, unsubstituted or mono-substituted by hydroxy,cyano, phenyl or alkoxy(C₁₋₄)carbonyl.
 26. A compound of claim 25,wherein R₅ is methyl, ethyl, benzyl or alkoxy(C₁₋₄)carbonyl methyl. 27.A compound of claim 23, wherein X is O.
 28. A compound according toclaim 1 wherein A.sup.⊖ is the methyl sulphate, ethyl sulphate, propylsulphate, chloride, bromide, p-toluene sulphonate, chlorozincate orbenzene sulphonate anion.
 29. A compound according to claim 1 whereinany alkyl as R₂ ', is methyl.